The role of inhaled corticosteroids in altering the course of chronic obstructive pulmonary disease is not well understood. The Lung Health Study is a multi-center clinical trial that is testing the hypothesis that inhaled triamcinolone 12ug daily will prevent the deterioration of pulmonary function in patients with mild to moderate COPD. In order to assess the potential for inhaled steroids to cause adrenal suppression, Cortrosyn TM stimulation tests are performed on individuals at baseline, one year, and three years after entry into the trial. The primary outcome measure will be the response at 30 and 60 minutes of serum cortisol. The comparison groups will be those treated with triamcinolone compared to those treated with a similar-appearing inhaled placebo. A total of 1017 patients are being studied at 10 centers throughout North America with a total of approximately 400 participating in this substudy. The other participating institutions include the University of California at Los Angeles, University of Oregon Health Sciences Center, Mayo Clinic, University of Alabama at Birmingham, Henry Ford Hospital, Case Western Reserve University, University of Manitoba, University of Pittsburgh, University of Minnesota (Coordinating Center), University of Utah and The Johns Hopkins University.